a. Field of the Invention
This invention relates to a process of roll-patterning and then painting a surface of a metal strip or sheet, particularly an aluminium strip or sheet used to form vanes or head or bottom rails for window covering assemblies, such as venetian blinds, or to form architectural panels for ceilings or wall coverings. This invention particularly relates to a painted metal strip or sheet with a decorative pattern on at least one surface, made by the process, and to a window covering assemblies and architectural panels made from the strip or sheet.
b. Background Art
Elongated vanes or slats of the type used in horizontal and vertical blinds are well known and commercially available. Such slats are formed, for example, by continuous casting of aluminium strips or sheets, subsequent milling and, if necessary, cutting to width to provide coils of aluminium strips having the desired thickness and width. Subsequently, the strips or sheets are painted (optional), then roll-formed and cut into slats of the desired length. Likewise, it is well known to roll-form and cut such strips or sheets into head and bottom rails and architectural panels.
Since window coverings and architectural products are frequently decorative, different colours and laminated or painted patterns are often provided on their exterior surfaces, particularly on the visible surfaces of slats and head and bottom rails of window coverings. In this regard, coiled strip, used to make blind slats, is normally covered with paint or lacquer in a coil-coating process in order to give it a decorative pattern before it is roll-formed into slats.
A pattern can then be rolled into the painted strip surface, so that the resulting indentations in the strip surface give it a fabric-like appearance. An example of a process and apparatus for providing such a pattern in a painted strip surface for foldable metal drape panels for vertical blinds is described in U.S. Pat. No. 4,362,039 (Toti). In the process of his patent, a rotary die is used to produce continuous patterns of scribe lines in painted surfaces of strips. The scribe lines assist in subsequently forming a preselected cross-sectional profile of the metal drape panels. Another rotary die is used for subsequently forming patterns of embossments in the strips between the scribe lines, in order to begin to stretch and work the metal between the scribe lines, so as to make it easier thereafter to form a weave pattern. Two additional rotary cutting die stations then cut the male and female hinges of the drape panel, and then, a rotary weave die station produces weave patterns between the scribe lines. The weave patterns comprise relatively deep cuts which slice through the metal at the edges of the pattern and provide a raised area which imitates the ins and outs of woven threads of cloth. Unfortunately, these cuts tend to damage the paint on the strip surface and can result in premature corrosion of the metal.
U.S. Pat. No. 4,499,938 (Toti) also describes a process and apparatus for making a metal blind slat by providing a relatively deeply embossed rib pattern in a painted strip material. The depth of the pattern is described as 0.015 inch (0.381 mm) in a strip of 0.008-0.010 inch (0.20-0.254 mm) thickness. This means that the depth of the pattern is more than the thickness of the strip, and so, the strip has been corrugated. Unfortunately, such an embossed pattern also inevitably tends to damage the paint on the strip and produce premature corrosion of the metal.